Accumulation Of Chromium Research Articles

Assessment of the phytoremediation potential of Zinnia elegans L. plant species for hexavalent chromium through pot experiment

Abstract Pot experiments were conducted in a completely randomisedstrip-plot design to investigate the root morphological variations, flowering stages (no. of buds, no. of buds blooming and no. of mature flowers) toxicological, physiological and biochemical changes in an ornamental plant Zinnia elegans (L.) using graded concentrations of hexavalent chromium (K2Cr2O7). The study also assessed the chromium bioaccumulation and translocation potential of Zinnia elegans from the contaminated soil. The physio-morphological parameters such as Chlorophyll a fluorescence transient (O–J–I–P), quantum yield of photosystem II ( φ P0), photosynthetic performance index of primary photochemistry (PI φ ), length of roots and shoots, biomass, total chlorophyll, carotenoid, protein, proline, reducing sugar content and activity of antioxidant enzymes viz guaiacol peroxidase (POX), ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) were analysed after 30, 45 and 60d of treatment. The experiment showed a relationship between an increase in the accumulation of chromium in root and shoot of plants and an increase in the concentrations of hexavalent chromium. However, the length, biomass, φ P0, PI φ , area under OJIP curve, chlorophyll and protein contents of the plants were decreased at higher concentration of Cr + 6 (75ppm). disturbance indices M 0 and V J derived from Chl. a fluorescence exhibited higher values indicating Cr + 6 induced stress at higher concentrations (>50ppm). However, the activity of antioxidant enzymes and proline contents were increased with the application of higher concentration of chromium, which indicates that the plants adaptive defense system relating to elevated Cr + 6 induced oxidative stress. The number of root hairs initially decreased with increase in the concentration of Cr + 6 but at higher concentration of Cr + 6 (75ppm) the number of root hairs were increased. The number of flowers and overall photosynthetic performance increased with the increase in Cr + 6 concentration up to 25ppm. At the highest concentration of Cr + 6 (75ppm), treated plants exhibited the least number of mature flowers. The experiments suggest that the Cr + 6 stress leads leads to early flowering in Zinnia elegans L. species. This study demonstrates that phytoremedation of Cr + 6 contaminated soils in mining sectors can be effectively carried out using non edible ornamental plants, thereby arresting the effects of the ion in the food chain.

Evaluation of chromium accumulation and resulting histopathological changes in Libyan jirds (Mammals, Rodentia), affected by effluent from Ghazghan leather industrial town, Iran.

The leather industry is one of the major producers of wastewater, releasing large amounts of various chemicals into the environment. Chromium (Cr) is the most commonly used agent in the tanning industry. Accumulation in the animal body can adversely affect the functioning of animal tissues. The current study investigated the toxic effects of Cr on lung, kidney, liver, and testicular tissues in Libyan jirds (Meriones libycus) inhabiting the area surrounding Ghazghan leather industrial town, Mashhad, Iran. Average Cr concentrations were found to be significantly higher in samples from contaminated areas than controls (p < 0.05). The highest accumulation of Cr was found in lung tissue, while the liver tissue showed the lowest. The results also showed that sex and age had no significant effect on Cr accumulation in any tissue at either sampling area (p < 0.05). Histological analyses showed that Cr accumulation had caused changes in tissue samples from Libyan jirds from the contaminated area. Hyperemia was observed in all tissues. In kidney tissue, necrosis and degeneration of the epithelial cells of the tubules were seen as well, and in one case, we also observed hemorrhage. In liver tissue, necrosis, degeneration, and inflammation were observed, along with one case, of fibrosis. In lung tissue, we observed emphysema, hemorrhage, and inflammation. Testicular tissue also showed a considerable lesion. Given the proximity of specimens' habitat to an area of importance, i.e., the industrial town, and the species' dependence on its habitat for nutrition, Libyan jirds are particularly useful for monitoring. Thus, they can be used to monitor the level of contamination in future studies.

Soil and banana crops (Musa paradisiaca L.) risk by chromium (Cr) accumulation through leachate and its health risk assessment

The leachate efluen of Semarang landfill is directly flew to the upper course of Kreo river is a fact that make Kreo river is possibly contaminated by heavy metal. Many banana trees are planted around the contaminated0soil. This study was conducted to determine Cr toxicity on banana trees that grow on contaminated soil and to determine public health risks that is caused by leachate of Semarang landfill. The measurement of bioaccumulation factor as the basic data for environmental safety and as the evaluation of wastewater processing is conducted through Cr level measurement. The research shows 1) Cr concentration on WWTP Jatibarang Semarang landfill’s efluen leachate in the rainy season exceeds the environmental safety limit. 2) Cr concentration in the water before and the after of efluen leachate contamination is under the standard. 3) Cr contamination in the soil around Jatibarang landfill’s efluen leachate contamination area exceeds its limit. 4) The bioconcentration factor shows the banana trees can accumulate Cr from soil to the tree. 5) Most of Cr accumulation in the banana trees is translocated to the air and to the root of the tree. 6) The banana plants such as root, stem and pseudostem from the Cr contaminated soil is safe for consumption.

Heavy Metals in Several Soybean Varieties Cultivated in the Transylvanian Plain, Romania

Soybeans are species of legume that has become one of the most widely consumed food in the world, because they are easy to cultivate and very beneficial for human health. The quality of the cultivated plants, including the content of toxic heavy metals depends to a large extent on the contaminants present in the soils in which they are grown and the method of fertilization. Through this research we aim to highlight the degree of accumulation of cadmium, chromium, cobalt, copper, nickel, lead and zinc in relation with the cultivated soybean genotype and fertilization. Three soy varieties (Cristina, Felix and Onix) were cultivated in an experimental field located at Cojocna Experimental Didactic Center of the University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca. The above-mentioned heavy metals were determined from the harvested mature soybean seeds using inductively coupled plasma-optical emission spectrometry, using an Avio 200 instrument. The obtained results demonstrated that the accumulation of heavy metals in soybean seeds is influenced by the cultivated genotype and fertilization; the Onix variety is more prone to the accumulation of heavy metals, while the highest values of the above listed metals were recorded in the case of fertilizing with „Fertitel”.

A study on the transfer of chromium from meadows to grazing livestock: an assessment of health risk.

The present investigation was performed in different district of Punjab to determine the chromium level in soil, forages, and blood plasma of the small ruminants (goat and sheep). The results showed that the mean concentrations of chromium in the soil of Sargodha, Mianwali, and Bhakkar districts were ranged from 1.8 to 2.3, 3.01 to 4.99, and 2.04 to 2.87 mg/kg, respectively. The chromium level was higher in Mianwali compared with Sargodha and Bhakkar. The mean concentrations of chromium in forages which were used for feeding purposes were found between 0.672 and 1.631, 1.493 and 2.612, and 0.7804 and 1.047 mg/kg for Sargodha, Mianwali, and Bhakkar, respectively. The mean concentrations of chromium in blood plasma of goat which consumed the contaminated forages were between 0.666 and 1.269 mg/L in Sargodha, 0.657 and 0.752 mg/L in Mianwali, and 1.39 and 2.37 mg/L in Bhakkar. In blood plasma of sheep, the residual levels of chromium in the districts Sargodha, Mianwali, and Bhakkar were ranged from 0.673 to 1.384, 0.83 to 1.086, and 1.496 to 3.611 mg/L, respectively. In the present research, there was a higher concentration of chromium in blood plasma of sheep from Bhakkar and the lowest was in Sargodha. The chromium level in blood samples was found to be higher than the tolerable level of 1.0 mg/L in all districts. In light of these results, it was concluded that chromium levels in the soil and forages of all sites were present within the safe limit while in blood samples of sheep and goats were found to be above the acceptable limit. Sheep and goats also consume water from river, streams, and ponds and other contaminated water sources. So it might be the reason of higher level of chromium in their blood plasma. Hence, the proper monitoring of study sites will be necessary to prevent the excessive accumulation of chromium in ruminants in the near future.

Residual acidified biochar modulates growth, physiological responses, and water relations of maize (Zea mays) under heavy metal-contaminated irrigation water.

A field trial was carried out to examine the influence of residual acidified biochar (a 3:100 (w/w) mixture of citric acid and citrus wood biochar) on soil properties, growth, water status, photosynthetic efficiency, metal accumulation, nutrition status, yield, and irrigation use efficiency (IUE) of maize grown under salty soil and metal-contaminated irrigation water. The acidified biochar (ABC) was applied to faba bean in 2016/2017 in saline soil (electrical conductivity (ECe) 7.6dSm-1) with three levels 0, 5, and 10tha-1 with 4 replications. The results summarized that after a year of utilization, acidified biochar still significantly affected the growth and yield by improved soil properties and decreased maize uptake of sodium by transient sodium (Na+) binding because of its high adsorption capacity. Growth, physiology, and maize yields were influenced positively by ABC application, under metal-contaminated irrigation water. It was summarized that the utilization of ABC had a significant residual (P ≤ 0.05) effect on reducing nickle (Ni), lead (Pb), cadmium (Cd), and chromium (Cr) accumulation in maize under heavy metal-contaminated irrigation water. However, more detailed open-field experiments should be carried out to assess the long-term residual impacts of ABC for sustaining maize production under biotic stress.

Biofortification of chromium in fenugreek seeds

BackgroundFenugreek and chromium are known to have anti-diabetic properties and this has been well demonstrated by multiple studies. Researches have been undertaken to study thebiofortification of chromium (Cr3+) in fenugreek. Some of the researchers have studied the biofortification from the soil irrigated with tannery waste water or from soil amended by tannery-sludge, with a view of enhancing the anti-diabetic effect of fenugreek plants. The present research work was also undertaken to increase the chromium content of fenugreek seeds, but through direct treatment of chromium picolinate solution to fenugreek seeds. MethodsFenugreek seeds were procured and divided in four groups having three batches of 10 g seeds- treatment1, treatment2, control1 and control2. Control1 group was kept raw and was given no treatment and control2 group was germinated using double distilled water. Treatment1 and treatment2, on the other hand, were given treatment of 0.02 g and 0.04 g chromium picolinate solution, on first day and 0.01 g and 0.02 g chromium picolinate solution on second day, respectively. The germinated samples were then completely dried, powdered, digested with di-acid mixture and assayed using Inductively Coupled Plasma optical emission spectrometry method for chromium content. The treatment1 sample was selected for further nutritional analysis along with control1 and control2 group to compare the nutritional composition of raw, germinated and chromium treated fenugreek seed flour. Fifteen sprouts from treatment1 group (treatment1A group) and fifteen sprouts from control2 group (control3 group) were sown in earthen pots for the analysis of chromium content in seeds of new plants. ResultsThe fenugreek seeds treated with two different concentrations of chromium picolinate viz. treatment1 and treatment2 group attained 55 and 80 times higher chromium content as compared to control2 group, respectively. All the estimated minerals and bioactive compounds were significantly high (p ≤ 0.01) in germinated fenugreek seed flour and chromium treated fenugreek seed flour compared to raw fenugreek seed flour. Germinated fenugreek seed flour and chromium treated fenugreek seed flour were statistically comparable to each other in respect of all the parameters analysed. Hence, it was evident that enriching fenugreek seeds with chromium, did not affect the nutritional content of fenugreek seed by any mean. Also, there was no significant difference between the chromium content in seeds of control3 group and T1A group. ConclusionsTreatment of fenugreek seeds with chromium solution seems to be an efficient and safe method for increasing their chromium concentration as compared to application of chromium to the soil for biofortification with minimal to no chance of chromium accumulation and inheritance in next generation plants. However, there is a need of more research to see how reliable these observations would be when different chromium salts and/or varied chromium concentration are used.

Exercise Affects Blood Glucose Levels and Tissue Chromium Distribution in High-Fat Diet-Fed C57BL6 Mice.

Obesity is commonly associated with hyperglycemia and type 2 diabetes and negatively affects chromium accumulation in tissues. Exercise prevents and controls obesity and type 2 diabetes. However, little information is available regarding chromium changes for regulating glucose homeostasis in high-fat diet (HFD)-fed animals/humans who exercise. Therefore, this study explored the effects of exercise and whether it alters chromium distribution in obese mice. Male C57BL6/J mice aged 4 weeks were randomly divided into two groups and fed either an HFD or standard diet (SD). Each group was subgrouped into two additional groups in which one subgroup was exposed to treadmill exercise for 12 weeks and the other comprised control mice. HFD-fed mice that exercised exhibited significant lower body weight gain, food/energy intake, daily food efficiency, and serum leptin and insulin levels than did HFD-fed control mice. Moreover, exercise reduced fasting glucose and enhanced insulin sensitivity and pancreatic β-cell function, as determined by homeostasis model assessment (HOMA)-insulin resistance and HOMA-β indices, respectively. Exercise also resulted in markedly higher chromium levels within the muscle, liver, fat tissues, and kidney but lower chromium levels in the bone and bloodstream in obese mice than in control mice. However, these changes were not noteworthy in SD-fed mice that exercised. Thus, exercise prevents and controls HFD-induced obesity and may modulate chromium distribution in insulin target tissues.

Accumulation of chromium in Lemna minor under the effect of pH and EDTA variation and assessment of the treatment impact on Nile tilapia (Oreochromis niloticus)

Accumulation of chromium in Lemna minor under the effect of pH and EDTA variation and assessment of the treatment impact on Nile tilapia (Oreochromis niloticus)

Root morphological response of six peanut cultivars to chromium (VI) toxicity.

We investigated the hypothesis that root morphology plays a crucial role in the variation in chromium (Cr) accumulation among peanut (Arachis hypogaea L.) cultivars, using the relationship between Cr accumulation and morphological characteristics of six peanut cultivars determined under 0, 10, 25, 75, and 100μmolL-1 Cr(VI) via hydroponic experiment. Significant variations were observed in Cr accumulation and root morphological parameters among peanut cultivars at the five Cr levels. The Cr concentrations in plants exhibited 1.72-, 4.67-, 1.81-, and 2.91-fold variations within cultivars for 10, 25, 75, and 100μmolL-1 Cr treatments, respectively. Positive correlations were found for total Cr in plants with total root length (RL), root surface area (SA), and root volume (RV). Negative correlations were also observed between the percentages of Cr in shoots and specific root length. These results suggest that root system morphology may partly explain the variation in Cr accumulation among cultivars. Cultivars with greater RL, SA, and RV showed higher capability for Cr accumulation.

Distribution and risk assessment of some heavy metals in surface water, sediment and grey mullet (Mugil cephalus) from contaminated creek in Woji, southern Nigeria

The human health risk assessment associated with accumulation of nickel (Ni), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu) in the tissues (gills, livers and muscles) of grey mullet (Mugil cephalus) collected from the creek in the Niger Delta region of Nigeria was investigated. Surface water, sediment and fish samples were collected and analysed from June to September 2019; estimated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI) were determined. The mean concentration (mg/kg ww) of the tested metals followed the sequence: Cu (33.48 ± 15.54) > Cd (24.62 ± 12.11) > Pb (10.59 ± 9.12) > Cr (0.43 ± 0.66); while Ni was not detected in the sampled tissues. The HI for male and female (adults) are 7.612 and 7.840 respectively, while male and female (children) are 9.567 and 10.842 respectively.

Chromium Accumulation by Avicennia alba Growing at Ecotourism Mangrove Forest in Surabaya, Indonesia

Chromium Accumulation by Avicennia alba Growing at Ecotourism Mangrove Forest in Surabaya, Indonesia

Genotoxicity induced by hexavalent chromium leading to eryptosis in Ctenopharyngodon idellus

The initiation of eryptosis as a result of genotoxic action of Cr(VI), seen through micronucleus and comet assay in the peripheral erythrocytes of Ctenopharyngodon idellus was evaluated through RT-qPCR. For this, fish was exposed to sublethal concentration of hexavalent chromium (5.30 and 10.63 mg/L), and the blood was sampled on different endpoints (15, 30 and 45 days). Accumulation of chromium in the erythrocytes was also studied, which depicted a significant increase in toxicant concentration and time dependent manner. Both concentrations of hexavalent chromium induced DNA damage, visible in the form of comet tails. The presence of micronuclei in the erythrocytes was accompanied with occurrence of nuclear bud (NBu), lobed nucleus (Lb), notched nucleus (Nt), vacuolated nucleus (Vn), binucleated cell (Bn) as nuclear abnormalities; and acanthocytes (Ac), echinocytes (Ec), notched cells (Nc), microcytes (Mc) and vacuolated cytoplasm (Vc) as cytoplasmic abnormalities. The expression of genes related to intrinsic apoptotic pathway induced by Cr(VI) presented significant (p < 0.05) upregulation in the expression of p53, Bax, Apaf-1, caspase9 and caspase3, and downregulation of Bcl2; inferring the initiation of apoptotic pathway. The ration of Bax and Bcl2 also appended the apoptotic state of the erythrocytes. From the present investigation, it can be concluded that genotoxicity induced by hexavalent chromium lead to eryptosis in C. idellus.

Assessment of the heavy metal bioremediation efficiency of the novel marine lactic acid bacterium, Lactobacillus plantarum MF042018

Heavy metal pollution is one of the most serious environmental and human health risk problem associated with industrial progress. The present study was conducted with the goal of isolation and characterization of metal-resistant lactic acid bacteria (LAB) from the Alexandrian Mediterranean Seacoast, Egypt, with their possible exploitation in metal remediation. Lactobacillus plantarum MF042018 exhibited high degree of resistance, up to 500 and 100 ppm, to both nickel and chromium, respectively, with multiple antibiotic resistance (MAR) index above 0.5. In an attempt to improve chromium removal by L. plantarum MF042018, Plackett-Burman followed by Box-Behnken statistical designs were applied. An initial Cr2+ concentration of 100 ppm and inoculum size of 3% presented the best conditions for the accumulation of chromium by L. plantarum MF042018. The study was also navigated to assess the biosorption capacity of L. plantarum MF042018, the maximum uptake capacity (q) of both Cd2+ and Pb2+ was recorded at pH 2.0 and a temperature of 22 °C after 1 hr. The biosorption process of Cd2+ and Pb2+ was well explained by the Langmuir isotherm model better than the Freundlich isotherm. Furthermore, the results revealed that the use of L. plantarum MF042018 is an effective tool for the treatment of hazardous metal-polluted battery-manufacturing effluent. Therefore, the present study implies that L. plantarum MF042018 can be applied as a promising biosorbent for the removal of heavy metals from industrial wasterwaters.

Assessment of heavy metals distribution in Barguzin River aquatic system (Lake Baikal basin)

This study is devoted to the analysis of the distribution of heavy metals in the aquatic system of the Barguzin River. This is one of the largest rivers of the Baikal basin. The element composition of surface water, bottom sediments, water plants ( L., Potamogeton perfoliatus L., Hippuris vulgaris L., Nymphoides peltata (S.G. Gmelin) O. Kuntze) and fish (Abramis brama, Cyprinus rubrofuscus, Perca fluviatilis, Rutilus rutilus lacustris) of the Barguzin River is studied. The following sequence of the accumulation of metals in aquatic plants: Mn > Fe > u (Zn) > r > Ni > o > Pb > Cd > Hg is established. Hippuris vulgaris L. contains the highest concentration of the studied metals. In the distribution of metals over the body of the studied fish species the following sequence Zn Fe> Cu Mn Cr > Pb> Ni Cd> Hg is observed. There is an accumulation of zinc, manganese and chromium in fish scales, and iron, lead in the liver. The obtained data of the distribution of heavy metals broadens and clarify the understanding of the biochemical characteristics of aquatic system components. This research provides one of the important steps for the development of environmental standards and environmental risk assessments.

Correlation profile of the heavy metal distribution in the Pontastacus leptodactylus tissues

Arsenic (As), copper (Cu), nickel (Ni), zinc (Zn), manganese (Mn), lead (Pb), iron (Fe), aluminum (Al), cadmium (Cd) and chromium (Cr) accumulations were evaluated in the gills, hepatopancreas, exoskeleton, and muscles of Pontastacus leptodactylus (crayfish) (Eschscholtz, 1823). The highest metal accumulation was observed in the gills and hepatopancreas. It was detected a negative correlation between Cr-Pb, As-Cr in the muscle tissue. All other metals were displayed positive correlations with each other in the gills, hepatopancreas, and exoskeleton. Strong positive correlations were determined between Ni-Cd and As-Pb in the gills, Ni-Cd, As-Pb and Al-Zn in the hepatopancreas, Zn-Mn and Fe-Cu in the exoskeleton, Ni-Cd, As-Pb, Zn-Mn, Al-Mn, Fe-Cu and Al-Zn in the muscle (r= 1.000). PCA and cluster analysis generally were supported the correlations observed. The correlations between divalent metals may be expressed by the role of divalent metal transporter 1 (DMT1) in the gathering of these metals.

ANALYSIS OF THE DISTRIBUTION OF CHROME AND MERCURY IN THE MAIN COALS OF THE RED ARMY GEOLOGICAL AND INDUSTRIAL AREA

Increasing requirements for environmental protection in the coal mining industry in Ukraine stipulates the need for new scientifically grounded methods for forecasting the content of toxic and potentially toxic elements in rock mass, mining waste and coal enrichment which is mined by mines, as well as the environmental impact by enterprises of heat power industry. For this purpose it is necessary to have data about concentration, character and peculiarities of the distribution of toxic and potentially toxic elements, including mercury and chromium in the coal seams. The studies covered all territory of one of the most studied geological and industrial areas of the Donbas - Krasnoarmiiskyi. In the article, peculiarities of the distribution of mercury and chromium are considered and character of their spreading in the coal seams are established, weighted average concentrations in the coal of the main seams and suite are calculated. Hystograms of distribution of mercury and chromium content in coal seams, as well as dendrograms of clustering results by weighted centroid method of coal seams by their content, have been constructed and analyzed. The accumulation of mercury and chromium in the coal seams of the district is polygenic and polychronic. The main form of finding these elements in the coal seams is sorbed (on clay minerals and fusenized microcomponents), and for mercury also sulfide (in epigenetic pyrites).

Biochar impact on chromium accumulation by rice through Fe microbial-induced redox transformation

Iron (Fe) dissimilatory reduction might impact chromium (Cr) mobility in the rice rhizosphere, but it is poorly understood. We assessed rhizosphere microbes’ role in Cr immobilization and bioavailability by conducting the pot experiment to test different biochar sources (PMB - pig manure and PSB - pine sawdust) and phosphorus (P) levels impact on Cr mobility. Results showed that PMB application increased root biomass (23–65 %) and decreased root Cr concentration (46–74 %) regardless P treatment. However, P addition reduced root and shoot biomass in control and PMB treatments by 33–43 % and 25–26 %. Therefore, low P input is recommended in Cr-contaminated soil. Moreover, Geobacter was the key microbial groups which may be involved in promoting Cr release by increasing Fe dissolution. Finally, Geobacter and Fe dissimilatory reduction play a central role in Cr translocation and they should be considered in strategies to reduce rice Cr uptake by biochar application.

A cross-sectional study on school-age children living near a municipal waste incinerator: Urinary metal levels and renal impairment assessment.

To take an insight into the long-term accumulation of chromium (Cr) and cadmium (Cd) in school-age children living near an MWI and to assess their early renal impairment, we conducted a cross-sectional study in 2015. A total of 116 children from the exposure area and 122 from the control area were recruited. We measured the urinary levels of Cr (U-Cr) and Cd (U-Cd) by inductively coupled plasma mass spectrometry (ICP-MS), and detected three classic renal tubule indicators, including N-acetyl-β-d-glucosaminidase (NAG), β2-microglobulin (BMG), and retinol binding protein (RBP). The U-Cd and U-Cr levels in children living near the MWI were 0.11 and 1.57 μg/g creatinine, respectively. Both the U-Cd and U-Cr levels in the exposure group were lower than those in the control group, although only U-Cd showed a statistical difference (p < 0.01). The U-NAG and U-RBP levels in the exposure group were also statistically lower than those in the control group (0.80 vs. 1.74 IU/g creatinine, 0.26 vs. 0.48 mg/g creatinine, respectively). The U-Cd level in this study was positively correlated with the U-NAG level (r = 0.26, p < 0.01), as the U-Cr level was also positively correlated with the levels of U-NAG, U-RBP, and U-BMG (r = 0.21, 0.33, 0.18, p < 0.01, respectively). This study indicates that children living close to this particular MWI may not suffer considerable long-term accumulation of Cd or Cr, nor early renal impairment.

Implications of plant growth promoting Klebsiella sp. CPSB4 and Enterobacter sp. CPSB49 in luxuriant growth of tomato plants under chromium stress

The present study explores the potential of two chromium tolerant and plant growth promoting bacterial strains, Klebsiella sp. and Enterobacter sp. in luxuriant growth of tomato plants under chromium stress conditions. For the assessment of potentiality of the two selected strains, a pot scale experiment was setup with tomato plant under different levels of chromium contamination. In pot experiment, different plant growth parameters, oxidative stress tolerance and chromium bioremediation potential were studied upon inoculation of the selected bacterial strains. The results of pot experiment showed that both the strains were effective in promotion of plant growth and enhanced the plant biomass but Enterobacter sp. was more prominent in enhancement of root length, shoot length, fresh and dry weight, and nutrient uptake in tomato plant. The enhancement of enzymes to combat oxidative stress in tomato plant under chromium stress was also observed for both the strains. Both strains enhanced the levels of superoxide dismutase, catalase, peroxidase, total phenolic, and ascorbic acid in tomato plant under different levels of chromium stress conditions. The chromium phytoremediation potential of tomato plant upon inoculation of both the strains was also studied. The results of phytoremediation showed greater chromium accumulation in roots with poor translocation in shoot upon inoculation of Klebsiella sp. while no significant enhancement in chromium uptake by tomato plant was observed on inoculation of Enterobacter sp. compared to control. Thus, these two strains can effectively be used in luxuriant growth of tomato plant under metal stress conditions.